Color cathode ray tube having shadow mask frame formed to accommodate a support system



June 10, 1969 c w, z c c 3,449,512

COLOR GATHODE RAY TUBE HAVING, SHADOW MASK FRAME FORMED TO ACCOMMODATE A SUPPORT SYSTEM Filed April 24, 1968 Sheet Of 2 INVENTOR. CHARLES W. ZACH RICH ATTORNEY June 10, 1969 c. w. ZACHRICH 3,449,612

COLOR CATHODE RAY TUBE HAVINGISHADOW MASK FRAME FORMED TO ACCOMMODATE A SUPPORT SYSTEM Filed April 24, 1968 Sheet & Of 2 INVENTOR.

CHARLES W. ZACHRICH ATTORNEY US. Cl. 31385 6 Claims ABSTRACT OF THE DISCLOSURE A mask support frame having at least 3 walls and an instanding planar flange about the upper edge thereof formed with conformed pockets in a plurality of the walls at the jointure area between the walls and the flange to accommodate movement amplifying hinges of the frame support system and allow utilization of the planar instanding flange.

Background of the invention This invention relates to color cathode ray tubes of the shadow mask variety and more particularly to the shadow mask supporting frame utilized in such tubes. Tubes of this type are exemplified in US. Patent No. 2,986,080. It has been conventional practice in the color cathode ray tube industry to support the foraminous shadow mask of the tube from a relatively rigid frame structure and to support this assembly within the tube by means of cooperation between releasable leaf springs attached to the frame and studs formed on an inside wall of the tube.

To prevent overscanning of the screen by the electron beams with subsequent color impurities caused by stray electrons, a beam shield has generally been formed about the upper edge of the frame. This beam shield or flange projects inwardly toward the center of the tube a prescribed distance and prevents the electron beams from impinging upon the wall of the frame, and thus substantially reduces the aforementioned color impurities. Flanges of the type described above are exemplified in US. Patent No. 3,345,530.

Recent innovations in the frame support system to correct for impure color problems caused by the expansion of the mask-frame assembly from the heating effect of the scanning electron beam has led to modifications in the instanding flange of the frame. An exemplary support system of this type may be found described in US. Patent No. 3,330,980. The modification which was first adopted comprised reshaping the mask supporting frame so that in place of the planar flange the flange and wall were curved to conform to the spherical configuration of the screen. Thus, the center areas on all four sides of the frame were lower than the corners. This permitted utilization of the heat-compensating frame support system-which comprises units mounted substantially at the center of the wallswhich utilized an instanding movement amplifying hinge. The lower center areas permitted free movement of the hinge. While this system provided an adequate mounting means for the frame support system, the elimination of the planar flange introduced new overscanning problems with the consequent color impurities.

Objects and summary of the invention It is, therefore, an object of this invention to reduce or eliminate the above cited dis-advantages.

It is another object of the invention to enhance color cathode ray tube manufacture.

It is yet another object of the invention to provide a United States Patent shadow mask frame which is formed to accommodate a movement amplifying hinge of a frame supporting system while still maintaining the planar flange.

These objects are accomplished in one aspect of the invention by the provision, in a color cathode ray tube of the shadow mask variety, of means for supporting a mask in spaced relationship with the screen which comprises,

in combination, a frame for supporting the mask and a support system for the frame. The frame comprises a substantially rectangular structure having an upstanding rim or wall which has an instanding substantially planar flange around the upper surface thereof. The support system comprises a plurality of springs attached to the frame through the intermediary of a spring mounting member, at least two of which have formed thereon an instanding movement amplification hinge. The frame is formed to provide a like number of receptive areas for the hinges in the form of hinge receiving pockets formed at the jointure of the wall and the flange.

The frame structure and frame support system described above greatly enhances color cathode ray tubes since they utilize not only the heat compensating support system but the planar flange as well.

Brief description of the drawings FIGURE 1 is a diagrammatic sectional representation of a color cathode ray tube;

FIGURE 2 is an enlarged cross-sectional view taken along the line 2-2 of FIGURE 1;

FIGURE 3 is a plan view taken along the line 33 of FIGURE 2; and

FIGURE 4 is a perspective sectional view of the frame taken along the line 44 of FIGURE 2.

Description of the preferred embodiment For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the above-described drawings.

Referring now to the drawings with greater particularity, in FIGURE 1 there is diagrammatically shown a cathode ray tube 10 having a screen 12 comprised of a multiplicity of phosphor triads formed on the inside surface of the screen faceplate 14 in a manner well known in the art. Positioned adjacent the screen 12 and spaced therefrom is a substantially rectangular foraminous shadow mask 16 which is attached at its peripheral edge to a mask supporting frame 18 having formed around its upper rim an instanding flange 19. A source of electrons 20 is positioned in the neck 22 of tube 10 and may comprise a plurality of individual electron guns as is also well known in the art.

The support system 24 is shown in greater detail in FIGURE 2 and comprises a spring 26 which is attached at one end to frame 18 through the intermediary of a spring mounting member 28. Spring mounting member 28 comprises an upper portion 30 to which is attached spring 26, a lower portion 32 which is attached to an upstanding wall 34 of frame 18, and an instanding substantially U- shaped movement amplification hinge 36 which joins the upper and lower portions. The frame 18 is formed to provide receptive areas 37 to accept to the instanding hinge 36 without interferring with the operation thereof and in this instance is shown as being a pocket 40 (see FIG. 4) formed at the jointure of wall 34 and flange 19. Also, in this instance, pocket 40 is shown as having an equal height, measured in a direction parallel to the tube axis, and a varying depth, measured in a direction perpendicular to the tube axis, which gives the pocket when viewed in plan a substantially triangular configuration to accommodate the hinge; however, the shape of the pocket will be dictated by the configuration of the hinge. The utilization of this form of support allows the employment of the instanding planar flange 19 which is joined to the upper rim of frame wall 34. It is noted above that the use of the planar flange provides many advantages among which are: greater strength for the frame; better protection for the screen against overscanning of the electron beam; and greater protection from the earths magnetic field. Further, the pockets formed in the jointure area act as strengthening agents for the frame, thus providing a more stable structure.

The entire mask-frame assembly is supported Within the tube by means of cooperation between an aperture provided in the free end of spring 26 and inwardly projecting studs 42 positioned 'interiorly of the cathode ray tube f'ace panel. Generally, three of these mounting areas are utilized although it is contemplated that four or more also may be used. One such system is shown in FIGURE 3 wherein there is illustrated a plan view of a face panel having a major axis x--x and a minor axis yy. In the embodiment shown, one stud '42 is positioned on the y taxis and two studs are positioned in opposition to one and another on the x axis. The receptive areas 40 are formed so that at least two opposed ones are displaced in the same direction relative to one of the axes, in this instance the x axis. This arrangement is known as a bucking system and tends to equalize the forces generated in the support system by heat-caused expansion of the elements during tube operation. Other mounting arrangements are known and may be utilized without departing from the invention.

There has thus been provided an enhanced cathode ray tube having an improved mask mounting system which incorporates a planar beam shield for the prevention of color impurities caused by over-scan of the electron beam.

[While there has been shown and described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

-I claim:

1. -In a color cathode ray tube of the shadow mask variety, means for supporting said mask in spaced relationship with the screen comprising in combination: a frame supporting said mask and a support system for said frame; said frame comprising a substantially rectangular structure having an upstanding wall having an instanding, substantially planar flange around the upper surface thereof; said support system comprising a plurality of springs attached to said frame through the intermediary of a spring mounting member, at least two of said mounting members having formed thereon an instanding movement amplification hinge; and said frame being formed to provide at least two hinge receiving areas formed as pockets at the jointure of said flange and said wall.

2. The tube of claim 1 wherein said pockets have a varying depth in a direction perpendicular to the longitudinal tube axis.

3. A substantially rectangular frame for supporting a foraminous electrode which comprises an upstanding rim defining four walls and having an inwardly projecting, substantially planar flange about the upper edge and attached to said wall at a jointure area; and a plurality of pockets formed in said frame at said jointure area.

4. The frame of claim 3 wherein said frame has a major and a minor axis and at least two opposed ones of said pockets are displaced in the same direction relative to one of said axes.

5. The frame of claim 4 wherein said one axis is said major axis.

6. The frame of claim 4 wherein said pockets have a varying depth in a direction perpendicular to the longitudinal tube axis.

References Cited UNITED STATES PATENTS 2,906,904 9/1959 Woughter et al. 313- 3,343,024 9/1967 Torrence 313-92 3,345,530 10/1967 Haas 313-85 X 3,377,493 4/ 1968 Levin et al. 31392 JAMES W. LAWRENCE, Primary Examiner. V. LAFRANCHI, Assistant Examiner.

U.S. Cl. X.R. 313-283, 292 

